Community gardens are already very popular in Berlin, but a group of agro-entrepreneurs is planning to take urban farming to the next level in the German capital. A team of three Berliners is planning to convert an enormous old malt factory in the city’s Schöneberg district into a rooftop farm that promises to be one of the most ambitious urban agriculture projects in the world. The Frisch vom Dach (“Fresh from the Roof”) project will be an aquaponics farm where both fish and vegetables are produced and distributed on-site.

Under the current plan, fish will be raised in the large vats that were once used to dry barley in the factory. Greenhouses will be constructed on the 7,000-square-meter roof, and waste from the fish will be used to fertilize the vegetables. The plants will in turn filter and purify the water for the fish, creating a sustainable, closed-loop system. In addition to selling vegetables year-round, the farmers will also harvest the fish and sell them as food.

Planning for the Frisch vom Dach farm began in September, and the founders hope to have their first harvest in 2013. The estimated cost to convert the factory into a farm is €5 million, and the team is currently courting investors. While they continue to plan and raise money for the rooftop farm, the Frisch vom Dach team has produced a small prototype out of an upcycled shipping container that they’ve dubbed “Little Brother” to experiment with aquaponics. The double-decker container farm is currently producing both fish and vegetables, and it’s on display in Berlin.